From:
Metz Rebekah [mailto:]
Sent: 07 December 2005 21:37
To:
Subject: RE: [soa-rm] Proposal:
Reorganization of SOA-RM Draft for Better
Gosh – if this
email came through in some weird format for everyone else, I am terribly sorry
about the wacky formatting of this email thread. Not sure if everyone saw
it as I did, but at least my outlook client puked =)
Uh-oh. We seem to
be starting to head back to the service as an object as opposed to an
act. I still do not believe that a service is an ‘object.’
In fact, I believe that assumption has caused much of the
difficulty in figuring out what a service actually is.
What is invoked is a
capability, consistent with the execution context and so to produce real world
effects. The actual invocation and performance of the capability is the
service; i.e. the action. Hence I maintain that visibility, interaction
and effect are the interrelated concepts often (yet confusingly) referred to
with a shorthand nomenclature of ‘service.’
[Jones, Steve G] Question this raises on the service in
terms of “act” or “object” are indeed multiple and
varied. I like the wording in the SOA-RM as (to me) it talks towards the idea
of containment, so a service is a container of actions (or processes) rather
than in itself being the action (Procurement is a Service, buy is the action).
As far as roles go, the
very essence of the word service is the recognition that <someone> does
<something> for <someone else>. I would agree that any other
specification of this generalization (uh…isn’t that an ontology)
belongs in something other than the RM.
Rebekah
Rebekah Metz
Associate
Booz Allen Hamilton
Voice: (703) 377-1471
Fax:
(703) 902-3457
From: Ken Laskey [mailto:]
Sent: Wednesday, December 07, 2005 4:19 PM
To: Metz Rebekah
Cc: Jones, Steve G; ; ; ;
; ;
; ; ;
Subject: Re: [soa-rm] Proposal: Reorganization of SOA-RM Draft for Better
inline
On Dec 7, 2005, at 4:00 PM, Metz Rebekah wrote:
Comments inline…
From: Ken Laskey [mailto:]
Sent: Wednesday, December 07, 2005 3:43 PM
To: Jones, Steve G
Cc: ; ; ;
; ; ;
; ;
Subject: Re: [soa-rm] Proposal: Reorganization of SOA-RM Draft for
Better
If I invoke a service, I am a service consumer. It does not matter
if I invoke the service on my own initiative or am told to do it (through a
targeted instruction or as part of a more complex set of instructions), I am
still the service consumer.
[->] Agreed.
I could glibly say that if I "provide" a service, I'm a
service provider, but I fear things are not that simple. Is the entity that
created the service its provider, or the one who maintains it, or the one who
hosts it, or the one who pays for it, or ...?
[->] I see this being a question of ‘what are the
roles’ versus ‘who plays the roles’. At first
pass, it seems right that we recognize the roles @ the RM level and leave the
details of determining the best way to decide how to assign some entity into
that role to the RA.
I think it is easy to start naming roles but difficult to stop, and
the roles will get more use-specific.
Luckily, from the RM standpoint, we don't care.
[->] or do we just delegate =)
... to someone who has no choice but to care ;-)
To be used within the context of SOA, the service must be visible,
must be able to take part in an interaction
[->] Here it sounds like the service is an active player in an
interaction. Isn’t it that the service consumer and provider
interact (as specified…?
Isn't the service an active player? I invoke it to get its real
world effect, so it certainly sounds like it does something.
(as specified by the established execution context), and must
produce a real world effect (which I assume may in some circumstances be null).
It has been "provided" but we don't care how or by whom.
So, in summary, there's a lot of muddy water but sometimes we can
avoid playing in it. :-)
[->] Or we can draw a circle around it and leave that to the RA
=)
... at which point you initially choose RA cases that you can more
cleanly defined. You eventually get to the tougher ones, but we should learn to
ride a bicycle before we get a motorcycle (unless Duane has a different
perspective)
Ken
[->] Rebekah
Ken
If I make a service available for someone to invoke (and here I
would say that "make available"
On Dec 7, 2005, at 4:47 AM, Jones, Steve G wrote:
To add some mud into the water…
Many Bus architectures do “enrichment” of messages
between consumer and producer, including the invocation of other services to
perform that enrichment (e.g stock quote returns current price, enrichment
provides the last ten days closing price). They may also do calculations
that result in the non-connection or “empty” return from the service
(e.g. if you call for “last five minutes trades” after the market
has closed… its an empty set). So while I agree that the service
consumer is key it’s sometimes hard to identify the true consumer and the
true producer of a service within a virtualised bus.
Steve
From:
[mailto:]
Sent: 06 December 2005 19:09
To: ; ; ;
; ; ;
;
Cc:
Subject: RE: [soa-rm] Proposal: Reorganization of SOA-RM Draft for
Better
I agree with Ken.
The service consumer is the key concept that indicates the entity
that invoked the service in the first place.
A brokering service or service actor is merely a middle-man.
Wes
-----Original Message-----
From: Ken Laskey [mailto:]
Sent: December 6, 2005 2:02 PM
To: ; ;
; ; ;
;
Cc:
Subject: RE: [soa-rm] Proposal: Reorganization of SOA-RM Draft for
Better
I could argue that a broker consumes the service on someone else's
behalf. In reality, service actor seems too nondescriptive because either
the consumer or the provider can be thought of as an actor.
Ken
At 01:45 PM 12/6/2005, wrote:
I hate to stir things up a bit, but can you change the service
consumer term to service actor?
Since in the case of brokering the service actor is not consuming
but brokering a request to another service.
The broker service can be a service actor upon the service but
might not really consume any part of the service since it is a pass through.
But I guess this is a matter of opinion.
- Dan
-----Original Message-----
From: Ken Laskey [ mailto:]
Sent: Tuesday, December 06, 2005 10:39 AM
To: Duane Nickull; Goran Zugic; Matt MacKenzie; MATHEWS, Tim; Sally
St. Amand;
Cc:
Subject: RE: [soa-rm] Proposal: Reorganization of SOA-RM Draft for
Better
I think we need to add some words to the RM to capture this
discussion. We cover part of this in the beginning of Section 3.2.1 but
need to be more specific that:
- a service consumer can be a human or a software agent;
- a service consumer can invoke any number of services (including a
single service in isolation) and can chain the output of some services to act
as the input of others;
- from the perspective of a given service, the occurrence of such
chaining would not be visible;
- the service consumer can be implementing a business process;
- the specific of a business process do not change the basic SOA
concepts as described in the RM; however, the specific architecture that one
designs and implements will reflect the business process and make use of
specific service instances that corresponds to the real world effects that the
business process hopes to realize.
Now that said, and in full appreciation that we agreed earlier that
mechanisms which combine services (e.g. choreography, orchestration) are out of
scope, is it sufficient for words, such as those suggested above, to be
included somewhere within the current discussion or do we need to pull it out
into a subsection on its own? As an example of the former, we tried to
deal with loose-coupling and coarse-grained with words at the end of Section
2.1.
Ken
At 12:23 PM 12/6/2005, Duane Nickull wrote:
Goran:
I slightly disagree with your assertions, probably based on
semantics. For a service to "participate" in a process, it
would have to be aware of the process (which many will not be). A better
way to depict this may be to state "services may be aggregated and used by
processes" and "processes may be represented/exposed as
services". There are really no limits to the number of layers that
can be present. Attached is a UML CVD depicting such.
A key rationale of why process is not part of SOA is that services
cannot see process. They are not aware of whether they are being called
as part of a process vs. as an individual service. If the "s"
part of SOA cannot see or touch that, it cannot be part of the RM.
The chicken and egg discussion you bring forward is a requirement
for those building services to strongly consider the business process when
designing their service infrastructure. Accordingly, it is not really
part of the RM for SOA yet I agree that it is a very important consideration.
For your messages to get to the list, you must join as a
"applicant" rather than an "observer" as per OASIS process.
Duane
*******************************
Adobe Systems, Inc. - http://www.adobe.com
Vice Chair -
UN/CEFACT http://www.uncefact.org/
Chair - OASIS SOA Reference Model Technical Committee
Personal Blog - http://technoracle.blogspot.com/
*******************************
From: Goran Zugic [ mailto:]
Sent: Monday, December 05, 2005 8:47 PM
To: Duane Nickull; Matt MacKenzie; MATHEWS, Tim; Sally St. Amand;
Cc:
Subject: Re: [soa-rm] Proposal: Reorganization of SOA-RM Draft for
Better
Duane,
Thanks for the response. Yes I would like to see the PPT. I hope
you do not mind if I add few more thoughts related to services and business
processes:
Services participate in a business process to add some value to it.
They can be governed and evaluated using business process metrics. One service
can participate in many business processes and provide value to each of them
according to the context within that process. As far as SOA is concerned it is
as important to know what the service does, how it can be discovered,
contacted, invoked, executed, etc. as it is to be able to use it within the
process context, measure it and assess its value from the business process
requirements point of view. SOA needs to avoid typical new technology chicken
and egg syndrome, e.g. companies not producing services because there are no
service friendly process definitions to use them and not having SOA friendly
process definitions because there are no services to use. Services do not have
to know if they will be involved in the process upfront, they will be contacted
on demand according to the process script that is in effect, and they will be
contacted, checked if available, passed the arguments, collected the response
and according to their procedure left alone to wait for another call. The
process execution engine however needs to invoke the service according to both
service specific information and the process specific information.
Having just the service specific information in a model covers only
one part of the picture and I think it is fine as long as that model is a pure
service model. However I find it difficult to understand that the SOA RM TC
model is a SOA reference model when it does not include other concepts of SOA.
Unfortunately it seems that we cannot get to the point where we could agree on
a minimal set of supported SOA concepts by a model to be the SOA RM. We do not have to and I do not want to argue with you or anybody else in SOA RM
TC. I am just trying to see how our works can fit together in a most efficient
way. We obviously need more time to better understand each others thoughts and
ideas and I strongly believe that a constructive respectable discussion is
helpful for everybody.
By the way, do you know what I am supposed to do to get my messages
to the SOA RM list. In spite of that I am the SOA RM TC observer I get a
faliure notice whenever I send a note to the SOA RM.
Goran
----- Original Message -----
From: Duane Nickull
To: Matt MacKenzie ; ; MATHEWS, Tim ;
Sally St. Amand ;
Cc:
Sent: Monday, December 05, 2005 5:02 PM
Subject: RE: [soa-rm] Proposal: Reorganization of SOA-RM Draft for
Better
Goran:
The service layer enables the process layer over top of it, however
during runtime, services do not know if they are part of a process or being
called individually (it would generally be a bad idea to try to maintain the
overall state of a process within each service, although it could be
done). For maximum repurposing of services, it would be better to have
the service as a simple slave to the processes that may use it.
Accordingly, we made a decision that BPM, Orchestration,
choreography is not a core part of the RM for SOA. We generally seem to
agree that many SOA implementations will include a layer of BPM over top.
We are only addressing the SOA model, not the model for the underlying or
overarching layers.
I have a PPT that explains this in more detail if you are
interested.
Duane
*******************************
Adobe Systems, Inc. - http://www.adobe.com
Vice Chair -
UN/CEFACT http://www.uncefact.org/
Chair - OASIS SOA Reference Model Technical Committee
Personal Blog - http://technoracle.blogspot.com/
*******************************
From: Matt MacKenzie [ mailto:]
Sent: Monday, December 05, 2005 12:51 PM
To: ; MATHEWS, Tim; Sally St. Amand;
Cc:
Subject: RE: [soa-rm] Proposal: Reorganization of SOA-RM Draft for
Better
Process orientation is only one of multiple potential integration
with service oriented architecture. SOA-RM is laying the foundation for
durable architecture based on the core concept of service orientation. We
recognize that process oriented architecture is a natural fit with service
orientation...but so are things like event orientation.
-matt
From: [ mailto:]
Sent: Monday, December 05, 2005 3:36 PM
To: MATHEWS, Tim; Matt MacKenzie; Sally St. Amand;
Cc:
Subject: Re: [soa-rm] Proposal: Reorganization of SOA-RM Draft for
Better
I think that SOA RM has done good job documenting well-known
service related concepts and defining some new ones.
I do not see other details besides service and service-related
concept definitions in the current SOA RM committee draft right now. I look
forward to seeing the completion of the model you are working on with the
bottom-up approach.
Business, business processes and collaboration aspects of business
are important to address in the model what is not the case with the current
content of the SOA RM committee draft. By a business process I mean a generic
business process entity which has common components (activities, decisions,
etc) and relationships between them that can be used to model a business
process in any environment regardless of what business we support and
technology we use. I agree with Sally that a link between business processes
and services should be one of key requirements any SOA reference model should
try to meet.
I am not sure what SOA with services brings to business when the
link between the business processes and services and overall business process
semantics in the SOA context are not considered to be important aspects in a
SOA-based reference model.
Goran
-----Original Message-----
From: MATHEWS, Tim [ mailto:]
Sent: Monday, December 5, 2005 12:34 PM
To: 'Matt MacKenzie', 'Sally St. Amand',
Cc:
Subject: RE: [soa-rm] Proposal: Reorganization of SOA-RM Draft for
Better "Componentization"
Matt - I am not sure what point you are trying to make by
this? I agree with your premise of a bottom up effort, as this was one of
the operating assumptions that was made from the beginning.
But, I am confident it is the business environment that is
independent from the reference model.
TM
From: Matt MacKenzie [ mailto:]
Sent: Monday, December 05, 2005 11:58 AM
To: Sally St. Amand;
Cc:
Subject: RE: [soa-rm] Proposal: Reorganization of SOA-RM Draft for
Better "Componentization"
Sally,
A reference model actually needs to be a bottom up effort. We
leave the ever so popular ?top-down? approach to folks like ebSOA J
We?re creating a vocabulary and general understanding of what I
hope we can call a discipline of computer science in the future. This
means, we need a durable reference model that is not dependent on the current
business environment.
-matt
From: Sally St. Amand [ mailto:]
Sent: Monday, December 05, 2005 10:19 AM
To:
Cc:
Subject: Re: [soa-rm] Proposal: Reorganization of SOA-RM Draft for
Better "Componentization"
Frank
This is in response to your request on last week?s conference call,
if anyone has comments speak now. I also think that the recent comments on
clarifying sections are a reflection of my issues with the specification.
I agree with the majority of points made/described in ver 10. My
issues are with what is not in this draft. Based on Fig 1 the Refe! rence Model
is guided by Reference Architectures, Concrete Architectures, Profile &
Related Models. They in turn account for requirements, motivation & goals.
This is creating a Reference Model from the bottom up. I believe a Reference
Model should reflect a top down approach.
The Reference Model needs to reflect the environment, the strategy
and the priorities of the business/mission/collaboration. This will
impact the construction of services. A service is a business task or activity
that is realized through technology. The draft does a good job of describing
how that realization happens. But it doesn?t provide a sufficient link between
processes and services. The draft makes the point that the central focus of!
SOA is the task of business function?getting something done. A business process
is made up of tasks and activities to achieve a goal (getting something done).
The concept of creating the service from the tasks and activities in a process
is important. For example, where on the continuum of fine grained to coarse
grained should a particular service be; this will affect interaction,
reusability. The relationship between processes and services needs to be in the
Reference Model.
While I saw that there is a note saying the glossary is still in
flux, since one of the objective of the Reference Model is a vocabulary, having
less in the glossary might be a better option. Is semantic integration a
guiding principle of SOA?
With respect to conformance there needs to be business results.
That is an SOA should provide demonstrable mission accomplishments, e.g. ROI,
match a competitors distribution channel. SOA is not a technology. Conformance
should provide operational accomplishments, these should be measurable.
Sally
!
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